Development of China digital soil map at 1:50,000 scale
W. L. ZhangA, A. G. XuA, H. J. JiA, R. L. ZhangA, Q. L. LeiA, H. Z. ZhangA, L. P. ZhaoA and H. Y. LongA
A
Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, 12 Zhongguancun South
Avenue, Beijing, 100081, China, Email [email protected]
Abstract
In order to meet the increasing demands for soil information of high resolution by different disciplines such
as agriculture, environment, economy, and so on, a China Digital Soil Map at 1:50,000 scale (CDSM50,000) has been developed since 1999. Soil and soil nutrient paper maps at 1:50,000 scale and soil profile
records were collected from 2,300 counties of China. These maps and records were achieved during the
period of the 2nd Chinese National Soil Survey from 1979 to 1985. A data model of CDSM-50,000 was
developed, which contains 9 map layers. Data of about 150,000 soil profiles were, for the first time, integrated
into CDSM-50,000. Every profile contains dozens of soil physical and chemical properties, such as soil
depth, texture, organic matter, pH value, contents of N, P, K, S, etc. Soil nutrient information of plough layer
samplings during the period from 1999 to 2008 was also collected and integrated into CDSM-50,000. To
merge different county soil maps with different mapping standards into one map according to the data model
of CDSM-50,000, a complicated soil data processing procedure was developed. Map data of 1,100 counties
had been already merged to CDSM-50,000. The data model was approved to be successful to organize all
soil survey information of China in the last 30 years. Hundreds of examined soil profiles were collected from
5 provinces to test the reliability of developed CDSM-50,000. A quite nice coherence was found between
CDSM-50,000 and the reality of soil type distribution. The finished digital soil maps were applied to cropland
nutrient management, arable land fertility evaluation, strategy for controlling eutrophication and for study for
climate change. This shows that CDSM-50,000 has played a great role for agriculture and environment.
Key Words
Digital soil map, soil profile, large scale, soil quality, organic matter.
Introduction
In China the arable land resources are very limited. According to newly published data, the arable land area
is 121.7 million hectares and the per capita arable land area is 0.092 hectares (Ministry of Land and
Resources of China 2009), just 40% of the world average. In the available arable land resources there are
only 1/3 are fertile soil. The rest are low or middle-low yield arable land. For achieving food security and
environment safety of the world most populated country, it is very important to understand the spatial and
temporal variation of soil quality precisely. In the beginning of 1980’s, a detailed soil survey work was
carried out in the whole country. For every counties, hand drawn soil maps at 1:50,000 scale were finished
based on large amount of soil profile observation. Since the very few hand drawn copies of paper maps and
soil profile records were storied in provincial or even in county bureaus separately, damages are seriously
due to acute organisation reform during last 30 years. Purposes of the study are to digitalize these paper soil
maps and records, to develop one digital soil model for the whole country, to merge the 2,300 county soil maps
and records together, and to enhance the application of soil information in agriculture, environment and economy.
Status of Soil Survey Work in China
A brief soil survey was carried out during the period from 1958 to 1960 in China (Li 1992; Anonymous
1964). A national soil map at 1:10,000,000 scale was drafted (Anonymous 1978). A more detailed soil
survey work was finished during the period from 1979 to 1985 (Li 1992). Dozens of thousand of soil
scientists and technicians were involved in the work. Based on large amount of soil profile observation and
soil sampling, maps of soil and soil nutrient content at 1:50,000 scale were drawn for every county
separately. Records of about 150,000 selected soil profiles, which presented main soil types of 2,300
counties in the whole country, were made. Each record contains dozens of soil characteristic such as soil
mother material, texture, and contents of soil organic mater, total nitrogen, available phosphorus, potassium
and pH in different soil layers with a profile depth of about 1-2 meter. In this survey, status of soil quality of
the whole country in the beginning of 1980’s was recorded. Recently, continuous attention has been paid to a
better understanding of soil quality. A national investigation for soil pollution has been started. Also a
national new investigation for soil nutrient status has been carried out since 2005. In these two
investigations, geo-coordinates of sampling spots have been acquired by using GPS. Main outputs of soil
survey in China in last 50 years were summarized in Table 1.
© 2010 19th World Congress of Soil Science, Soil Solutions for a Changing World
1 – 6 August 2010, Brisbane, Australia. Published on DVD.
13
Table 1. Soil survey and investigation work in China.
Period
Content
Main Output
1958-1960
1979-1985
Soil Survey
Soil Survey
Nutrient Status
2000s
Nutrient Status
Soil Pollutants
Soil Map of China, Report
Soil Maps, Reports (2,300 counties)
Soil Maps, Reports(28 Provinces)
Soil Map of China, Report
Soil Nutrient Maps (2,300 counties)
Soil Maps (28 Provinces)
Soil Nutrient Maps of China
Database, Reports (most counties of China )
Database, Reports (most regions of China)
Scale
Main
1:10,000,000
1:50,000
1:500,000
1:1,000,000
1:50,000
1:500,000
1:4,000,000
Range
1:25,000-1:200,000
1:200,000-1:1,000,000
1:25,000-1:200,000
1:200,000-1:1,000,000
Data Model of CDSM-50000 (China Digital Soil Maps at 1:50,000 scale)
Original paper maps of soil and soil nutrient content at 1:50,000 scale and profile records finished in 1980s
have been collected from different counties and provinces. Results of soil nutrient status sampled in 2000s
were also collected national widely. According to the temporal and geographical features of soil information,
a data model with 9 map layers was developed (Table 2). Soil information of 1,100 counties has already been
digitalized and merged into CDSM-50,000 (Figure1). The data model has been approved to be successful to
organize the miscellaneous soil survey information at county level obtained from 1980s up to now. Hundreds
of examining soil profiles was collected from 5 provinces to test the reliability of developed CDSM-50,000.
Quite nice coherence was found between CDSM-50,000 and the reality of soil type distribution.
Table 2. Data model of CDSM-50,000 (China Digital Soil Maps at 1:50,000 scale)
Map layers
Geo-feature
Temporal feature
Soil types
Polygon
Organic matter
Polygon
Total nitrogen
Polygon
1979 to 1985
Available phosphorus
Polygon
Available potassium
Polygon
pH
Polygon
Soil profiles
Point
Soil profiles
Point
2000s
Plough layer soil samples
Point
Mapping of CDSM-50,000
To merge different county soil maps with different mapping standards into one map according to the data
model of CDSM-50,000, a complicated soil data processing procedure was developed. By using this
procedure Soil Map of China at 50,000 scale has been developed and plotted. The whole map contains
24,000 sub-maps. Two map layers concerning with soil information and necessary basic geographic
information (Figure 2). One layer shows distribution of soil types, which was demonstrated by using Soil
Classification System developed and widely applied in China (Anonymous 1998). Also soil classification
system developed by Gong, which was more adjacent to the system applied in USA was parallel listed (Gong
1999). Through linkage between two soil classification systems, scientists of other country can easily find
out the required soil information. The other map layer is soil profiles, which was, for the first time,
introduced into the map. Positions of representative profiles of main soil types were labelled on the map
(Figure 2). Tables of soil profile characteristics were attached on the map, which showed physical and
chemical features of different depth of every representative soil profile labelled on the sub-map. An example
was demonstrated in Table 3. The basic geographic information on the soil map includes map layers for
administration region, water system, residential area and topographical information.
Application
By using CDSM-50,000, it is easy to get detailed soil information from different places and period in China.
Besides improving crop nutrient management for farmers, CDSM-50,000 has also been applied in research
works. An analysis of soil fertility changes of arable land in China was showed simply by calculating data
provided by CDSM-50,000 (Table 4). It showed that the content of soil organic matter in arable land in about
25 years increased by 33% in China. If we use the arable land area with 121.7 millions hectares and plough
layer depth with 20 cm, the net increase of carbon arrived to 953 million tons for the whole country. That
means 3,494 million ton carbon dioxide has been additionally fixed in soils. Through advanced farming
© 2010 19th World Congress of Soil Science, Soil Solutions for a Changing World
1 – 6 August 2010, Brisbane, Australia. Published on DVD.
14
⑧
⑤
③
⑩
⑨
⑦
⑤
①
②
Digitalized county
Collected county
⑥
④
①: Soil profile
(Attributive data of soil profile were listed in Table 3)
Figure 1. The collected and digitalized soil
information by using model of CDSM-50,000.
Figure 2. Soil Map of China, Sub-map: Ledu, Ledu
county, Qinghai Province.
EC
(mg/100g)
Total K
(g/kg)
Total P
(g/kg)
Total N
(g/kg)
OM
(g/kg)
pH
Soil
depth
cm
loess
old red soil
deposit
loess
Soil layer
6.8
5.3
7.1
14.2
16.1
11.4
6.8
7.1
10.8
9.2
6.6
Parent
material
A
0-12
silty clay loam 9
6.3
0.65
1.64
24.7
2
76
B1
12-70
silty
clay
loam
8.9
2.3
0.44
1.55
23.5
2
82
①
B2
70-150
silty clay
9.2
1.7
0.4
1.85
24.8
3
116
A1 0-15
silty clay loam 8.5
30.8
2.31
1.69
25.9
2
212
A2 15-30
silty clay loam 8.4
23.9
1.87
1.45
24.6
3
88
②
B
30-50
silty clay loam 8.5
13.9
1.13
1.1
21.6
1
64
C
50-150
silty clay loam 8.4
6.4
0.64
1.13
20.2
3
58
A
0-18
sandy loam
8.2
9.8
0.75
1.43
22.2
3
170
B1
18-70
silty clay loam 8.4
12.3
1.09
1.69
19.9
3
94
③
B2
70-124
silty clay loam 8.2
8.2
0.72
1.54
18.7
2
72
C
124-150
silty clay loam 8.6
5.2
0.43
1.45
21.1
1
63
*Example Table was attached to Soil Map of China, Sub-map Name: Ledu, Ledu county, Qinghai Province, Soil
profiles were sampled and analysed in 1982-1983.
**Profiles listed in Table 3 were labelled on figure 2.
Profile
Lable**
Available
K(g/kg)
Available P
(g/kg)
Soil texture
Table 3. Example table of soil profile characteristics*
Table 4. Change of soil organic matter, available P and K of China.
Soil parameters
1979 to 1985
2000s
Increase
Organic matter*
(%)
1.82
2.42
33%
n
1,151,366
85,512
Available
(mg/kg)
7.9
18.8
138%
phosphorus**
n
907,502
56,515
Available
(mg/kg)
105
119.08
13%
potassium***
n
667,673
45,225
* Determination of C; ** Determined mainly by Olsen method; *** Abstracted by NH4OAC.
practices and soil fertility improvement in China, not only yield increased greatly, but also 139.9 million ton
carbon dioxide additionally fixed annually during the last 25 years. It also shows that the concentration of
soil available phosphorus increased by 138% and the concentration of soil available potassium increased
slightly. With large number of soil samplings from the whole country, the analysis provides a reliable
nutrient variation of arable land. Also other evaluations of arable land fertility changes, food security, and
environment safety in the country, in a region or in a watershed have been implemented with the help of
CDSM-50,000 (Li 2004; Zhang et al. 2004). With completeness and continuous enrichment of CDSM50,000, it will play more important roles in agriculture, environment and research works.
© 2010 19th World Congress of Soil Science, Soil Solutions for a Changing World
1 – 6 August 2010, Brisbane, Australia. Published on DVD.
15
References
Gong ZT, ZC Chen, XZ Shi (1999) ‘Chinese Soil Taxonomy: Theories, Methods and Practices’. (Science
Press: Beijing, In Chinese)
Li QL (2004) Study on environmental fate of DDTs in Tianjin and Taihu Lake Region, Master Thesis,
Beijing University, Beijing, China. (In Chinese).
Li XR, P Lin, CX Li (1992) ‘National Soil Survey Technique of China’. (Agriculture Press: Beijing, In
Chinese).
Ministry of Land and Resources of China (2009) ‘Arable Land Area Newly Published by China’.
www.news.xinhuanet.com/newscenter/2009-02/26/content_10904418.htm.
Anonymous (1978) Classification and distribution of soils. In ‘Soils of China’. (Eds Nanking Institute of Soil
Science, Academia Sinica ) pp. 441-459. (Science Press: Beijing, In Chinese).
Anonymous (1964) ‘Agricultural Soils in China’. (National Soil Survey Office: Ministry of Agriculture) (In
Chinese).
Anonymous (1998) Soil classification. In 'Soils of China'. (Eds Xi CF, Zhu KG, Zhou MZ, et al ) pp. 31-54.
(China Agriculture Press: Beijing). (In Chinese).
Zhang WL, SX Wu, HJ Ji (2004) Estimation of Agricultural Non-point Source Pollution in China and the
Alleviating Strategies I: Estimation of Agricultural Non-point Source Pollution in China in Early 21
Century. Scientia Agricultura Sinica 7, 1008-1017 (In Chinese).
© 2010 19th World Congress of Soil Science, Soil Solutions for a Changing World
1 – 6 August 2010, Brisbane, Australia. Published on DVD.
16